This invention relates to an indicating device for the recovery of skiers buried by avalanches, using a search and rescue system which operates with transmitters and receivers.
Skiing is becoming a widespread sport which is increasing in popularity. Existing ski resorts are frequently very large. Due to the increasing popularity of the sport, these ski areas are expanding. Completely new areas are constantly being developed.
The danger of skiers becoming the victims of avalanches is increasing, particularly as the willingness of skiers to take risks is also increasing. The existing, marked ski runs or pistes are frequently being left behind in order to enjoy the pleasures of deep powder. For these kinds of areas there is often an increased danger of avalanches. Therefore, the rapid recovery of victims of skiing accidents is a demand which is becoming more and more urgent not only for the skiers but for the operators of the ski resorts as well. The technical means known to date have not been able to fulfill this demand satisfactorily, especially in view of the fact already mentioned that skiing has become a sport of such broad popularity.
Search and rescue systems operating with transmitters and receivers as such are known. These include a direction finding and search device normally used by search teams or rescue organizations and which is equipped with a transmitter and a receiver. The power supply of this device is not problematic, because the device can be supplied power either by the mains or, if it is only used in the course of a rescue action, by rechargeable batteries. The batteries in the device can thus be charged or replaced before each employment.
Each endangered person is equipped with an indicator device, which contains a receiver tuned to the frequency of the search transmitter, as well as a transmitter. If there is an emergency, a signal is transmitted with the aid of the search device. If such a signal is received by the receiver of the indicator, the indicator-transmitter is switched on. The signals of this transmitter are received by the receiver of the search device. Using these signals the location of the avalanche victim can be quickly found.
One basic problem exists with respect to the power supply of indicator devices of this type as noted in Swiss Patent No. 514 897 and the German Patent Publication No. 25 45 066. These indicators must be equipped with their own power supply, such as a battery, to realize a sufficient transmission range (active operation of the indicator). The constant operation of the indicator leads to the rapid discharge of the battery, so that the function of the indicator can no longer be fulfilled. If the indicator can be switched on and off manually, then the danger exists that the bearer of the indicator will forget to switch the device on. To solve this problem, it has been suggested that batteries be placed in the soles of the ski boots, which is inconvenient and problematic, as indicated in the German Patents Nos. 24 25 444 and 24 37 981 and that complicated battery charging systems be set up in areas where endangered skiers congregate, as indicated in the German Patent No. 31 09 283. In the case of skiing, a sport practiced by large numbers of people, such systems are impractical due to their complexity and the high cost. Consequently, these systems have not been able to penetrate the market. Although indicators are known which operate passively, i.e. indicators without their own power source as disclosed in the German Patent No. 23 52 807 as well as the German Patent Publication Nos. 24 37 464 and 32 11 381, these devices are not suitable for locating skiers buried by avalanches since the transmitters of such indicators have only a very short transmission range.